The present invention relates to a coupling, and more particularly to a compressive stress coupling arrangement having a third material between a ceramic component and a metal component.
Turbine inlet temperature strongly influences the thermal efficiency of a gas turbine: higher turbine inlet temperature generally leads to thermally more efficient gas turbines. However, higher turbine inlet temperature requires temperature and oxidation resistant materials such as ceramics. These components include ceramic turbine rotors that are typically attached to a metal shaft such that power is transmitted from the turbine rotor to a compressor rotor.
Connecting the ceramic turbine rotor to the metal shaft requires particular structural arrangements as ceramics thermally expand less than metals. The difference in thermal expansion results in thermal stress that may lessen the connection between the ceramic rotor and the metallic shaft. To maintain an effective joint between the rotor and the shaft, various brazing, shrink-fit compliant intermediate layers as well as mechanical clamp structures have been employed.
Accordingly, it is desirable to provide a shrink fit coupling for coupling a ceramic member to a metal member that is capable of transmitting torque at relatively high temperatures.